Digital television receiver converting vestigial-sideband signals to double-sideband AM signals before demodulation
AssigneeSamsung Electronics Co., Ltd.
InventorAllen LeRoy Limberg
Life of this patent
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Abstract
A vestigial-sideband (VSB) signal is converted to a double-sideband amplitude-modulation final intermediate-frequency signal that is subsequently detected to generate a baseband demodulation result. The carrier of this final I-F signal has a carrier offset from zero-frequency, which carrier offset exceeds the highest modulating frequency of the VSB signal and is adjusted to a prescribed carrier offset value. The double-sideband amplitude-modulation final I-F signal is generated by combining the VSB signal with its image.
Claims43
A method for converting a vestigial sideband amplitude-modulation signal to a double-sideband amplitude-modulation signal containing similar information, said method comprising the concurrent steps of:
- mixing said vestigial sideband amplitude-modulation signal with a first beat frequency different from the frequency of its own carrier, said first beat frequency being of such value as to generate a first mixing result that is translated in frequency to have its carrier at an offset frequency and;
- mixing said vestigial sideband amplitude-modulation signal with a second beat frequency different from the frequency of its own carrier and from said first beat frequency, said second beat frequency being of such value as to generate a second mixing result that is translated in frequency to have its carrier at said offset frequency;
- and
- combining said first and second mixing results, which have respective frequency spectra that are images of each other, to form said double-sideband amplitude-modulation signal with its carrier frequency at said offset frequency.
A method for converting a vestigial sideband amplitude-modulation signal to a double-sideband amplitude-modulation signal containing similar information, said method comprising the concurrent steps of:
- mixing said vestigial sideband amplitude-modulation signal with a beat frequency signal twice the frequency of its own carrier to generate, as a downconversion result, an image of said vestigial sideband amplitude-modulation signal having the same carrier frequency as said vestigial sideband amplitude-modulation signal;
- and
- combining said vestigial sideband amplitude-modulation signal with said image thereof having the same carrier frequency, to form said double-sideband amplitude-modulation signal.
Dependencies are inferred from the claim text.